1. Field of the Invention
The present invention relates generally to a mobile communication system, and more particularly, to an apparatus and a method for processing an unrecoverable error in a Radio Link Control (RLC) of a terminal.
2. Description of the Related Art
A Radio Bearer (RB) is used for conveying control plane data and user plane data on a Uu interface. The RB is classified into two types; a signaling RB and a data RB.
The signaling RB conveys control plane data and corresponds to an RB IDentifier (RBID) (0, 1, 2, 3, 4). In addition, the RBID (0, 1, 2, 3, 4) is classified depending on a service mode, where RBID 0 relates to a Transparent Mode (TM), RBID 1 relates to an Unacknowledged Mode (UM), and RBIDs 2, 3, and 4 relate to Acknowledged Modes (AM). Here, in AM, an ACKnowledgement (ACK) is transmitted to an object entity with respect to a Protocol Data Unit (PDU).
The data RB conveys user plane data and corresponds to RBIDs 5 to 32. In these RBIDs, any mode (AM, UM, or TM) is possible depending on network settings.
When a terminal receives a downlink reset message and resets a lower layer, it is often detected by a Radio Resource Control (RRC) layer that an RLC layer transmits an unrecoverable error.
Even in this case, when the reset is completed, the terminal transmits a response message to a network, which wastes data, because the RRC layer should process the unrecoverable error and so an exclusive connection release is required, which represents that data transmission is instantaneously disconnected.
To recover the unrecoverable error, the RRC layer transmits a cell update message to a counterpart node and then receives a cell update confirm message. Thereafter, the RLC layer performs synchronization with a counterpart RLC layer by performing a re-establishment process with respect to a transmission side and a reception side.
However, this process wastes resources because the same process is simultaneously performed in both the reception side and the transmission side, and because it takes too much time for the terminal to return to an exclusive connection mode.